In a multi-carrier deployment wireless communications systems a number of different base station attachment points may be available to an access terminal at the same time. Some of the different available base station attachment points may correspond to different carriers. Communications capabilities between the access terminal and the different available attachment points can be expected to be different for different attachment points at different times, e.g., as a function of access terminal location, transmission signal strength, channel gain, interference, noise, etc. In addition attachment point loading conditions can be expected to vary throughout the system.
It is desirable to be able to efficiently utilize the available air link resources in a system including multiple carriers and multiple alternative attachment points to maximize throughput and enhance user experience. Load balancing in such a system is an important consideration. There is a need for a handoff mechanism that facilitates load balancing in a multi-carrier system. A centralized system control node approach to load balancing may not be practical or efficient to implement, e.g., due to system architecture, control signaling overhead and/or control signaling delays.
A mobile access terminal may be in the best situation to evaluate its current channel conditions with respect to potential alternative attachment points. Based on the above discussion, there is a need for novel access terminal based handoff decision methods and apparatus which facilitate load balancing in a multi-carrier wireless communications system. In addition, to load balancing maintaining stability is another important consideration in a communications system. It would be beneficial if any new access terminal based handoff methods and apparatus also employed techniques which contributed to system stability.